AN INFRARED INVESTIGATION OF THE CATALYST FORMATION IN THE SYSTEM Nl(acac)2, C3H4, (iBu)&l FOR PROPADIENE POLYMERIZATION

The catalyst formation in the system Ni(acac),, C&I,, (iBu)sAl was investigated by means of infrared spectroscopy. It was found that the Al(acac)s and (iBu)&l(acac) formed are both by-products of catalyst formation without a catalytic activity. Ni(acac)z loses its acac groups forming the unstable (iBu)sNi compound; without CsH, being present, this compound disproportionates to Ni metal and isobutane and isobuteneIn the presence of C&H, an ally&nickel complex is formed, which reacts with (iBu)sAl to give the actual catalyst, possibly a bimetallic allyl-nickel-al uminium complexCatalysts such as Ni(acac)s, Cs&, (iBu)sAl and (aCsHs)zNi with or without (iBu)&l all selectively give 1, 2, I, 2-polypropadieneA Lewis base like pyridine not only decreases the polymerization rate but also changes the selectivity towards the formation of 1, 2,2, l-polymer.